Antenna and acoustic horn apparatus

ABSTRACT

DISCLOSED ARE ANTENNA AND ACOUSTIC HORN APPARATUS USABLE IN PORTABLE COMMUNICATIONS UNITS, SUCH AS TRANSCEIVERS. ONE SUCH APPARATUS INCLUDES A DIELECTRIC ACOUSTIC HORN POSITIONED WITHIN THE VOLUME OF SPACE BETWEEN TWO PARALLEL PLATES OF AN ANTENNA. THE ACOUSTIC HORN, WHICH TOGETHER WITH THE AIR IN THE VOLUME COMPRISES DIELECTRIC BETWEEN THE ANTENNA PLATES, PROVIDES A PATH OF VARYING ACOUSTIC IMPEDANCE FOR MATCHING THE ACOUSTIC IMPEDANCE OF FREE SPACE TO THE ACOUSTIC IMPEDANCE OF A TRANSDUCER, ALSO INCLUDED IN THE APPARATUS, FOR MORE EFFICIENTLY COUPLING AN ACOUSTIC SIGNAL THEREBETWEEN. AN INDUCTIVE TUNING DEVICE IS CONNECTED BETWEEN THE ANTENNA PLATES TO COMPENSATE FOR THE CAPACITIVE EFFECTS OF ANTENNA DIELECTRIC. OTHER EMBODIMENTS ARE ALSO COVERED.

197-1, w. E. BUEHRLE, JR, EIAL 3,555,422

ANTENNA AND ACOUSTIC HORN APPARATUS Filed Feb. 20, 1969 l2 M 2 v /'L l/I//////// '56 Z 5c .3 U L/i l6 l/l "'60 loo United States Patent US.Cl. 32516 12 Claims ABSTRACT OF THE DISCLOSURE Disclosed are antenna andacoustic horn apparatus usable in portable communications units, such astransceivers. One such apparatus includes a dielectric acoustic hornpositioned within the volume of space between two parallel plates of anantenna. The acoustic horn, which together with the air in the volumecomprises dielectric between the antenna plates, provides a path ofvarying acoustic impedance for matching the acoustic impedance of freespace to the acoustic impedance of a transducer, also included in theapparatus, for more efiiciently coupling an acoustic signaltherebetween. An inductive tuning device is connected between theantenna plates to compensate for the capacitive effects of antennadielectric. Other embodiments are also covered.

SUMMARY OF THE INVENTION This invention relates to communicationssystems and more particularly to transmitting, receiving and transceiverunits usable in such systems.

It is often desirable, especially with regard to portable communicationunits, that these units contain as little unused space as possible.However, even relatively compact units often contain antennas in whichthe antenna plates are separated from each other by a volume of spacewhich is not utilized other than in providing the prescribedplate-spacing itself.

Objects of this invention are, therefore, to better utilize the volumeof space between antenna elements; to utilize this volume in theefficient coupling of acoustic signals; and, further, to provide suchcoupling without appreciable degradation of the performance of theantenna.

In accordance with the present invention, there is provided an integralantenna and acoustic horn apparatus usable in a portable communicationsunit, comprising an antenna including two plates having a prescribedseparation therebetween, the separation between the plates defining avolume of space and transducer means responsive to a supplied signal forconverting the supplied signal into another predetermined type ofsignal. The apparatus further includes dielectric acoustic horn meanspositioned within the volume between the antenna plates and coupled tothe transducer means for matching the acoustic impedance of free spaceto the acoustic impedance of the transducer means for more efficientlycoupling an acoustic signal therebetween, the acoustic horn togetherwith air in the volume comprising dielectric between the antenna platesso that the impedance matching is provided without any appreciabledegradation of the antenna performance.

BRIEF DESCRIPTION OF THE DRAWINGS shown contained in a portable,hand-held transceiver unit usable for communicating with various fixedand mobile stations.

3,555,422 Patented Jan. 12, I971 ice ' FIGJZ depicts a partlysectionalized view of one form of antenna and acoustic hornapparatusalso in accordance with the invention; i

FIG. 3 depicts an isometric or perspective view of another form ofantenna and acoustic horn apparatus in accordance with the invention;

FIG. 4 is a sectionalized top view of still another form of antenna andacoustic horn apparatus in accordance with the invention; and I FIG. 5depicts yet another form of antenna and acoustic horn apparatus, also inaccordance with the invention.

DESCRIPTION OF THE INVENTION There is depicted in FIG. 1 a perspectiveview of an audio communications system having one type of antenna andacoustic horn apparatus 10 in accordance with the invention. In thisparticular embodiment apparatus 10 is shown contained in a portable,hand-held transceiver unit used for communicating with various fixed andmobile remote stations.

One form of apparatus 10 is shown in some detail in FIG. 2. Here,apparatus 10' includes antenna 11 of conventional construction andhaving substantially parallel first and second antenna plates 12 and 13,the separation between these plates defining a volume of space. Alsoincluded in apparatus 10 is transducer means, microphone 14, responsiveto a supplied substantially acoustic signal such as one supplied from anacoustic horn means, acoustic horn 15, for converting the signal into asubstantially nonacoustic signal such as an electrical signal which maythen be coupled to circuitry (not shown) in the transceiver unit fortransmission to the remote stations via antenna 11. Further included inthe embodiment of FIG. 2 is a second transducer means, acousticgenerator 16, responsive to a second supplied signalthis one beingsubstantially nonacoustic such as an electrical signal coupled fromcircuitry (not shown) in the transceiver unitfor converting the secondsupplied signal to a substantially acoustic signal to be coupled to theacoustic horn 15.

Additionally included in apparatus 10 is dielectric acoustic horn means,depicted as previously mentioned acoustic horn 15, which may be ofplastic or any other suitable dielectric material. Acoustic horn 15,which approximates an exponential acoustic horn although other types ofhorns such as logarithmic, and the like may be used where appropriate,is positioned and conventionally mounted within the volume of spacebetween antenna plates 12 and 13. Acoustic horn 15 can be mounted to thewalls of plates 12, 13 or in any other appropriate manner depending uponthe desired size and configuration. The larger end of exponentialacoustic horn 15 is shown open to the air, i.e., free space, and theother end .is shown connected via tubing or any other convenientconnecting means to both the input of microphone 14 and the output ofacoustic generator 16. Acoustic horn 15 thus is for coupling an acousticsignal from free space to microphone 14, and for additionally coupling asecond acoustic signal from acoustic generator 16 to free space.

Acoustic horn 15 thus provides a path of varying acoustic impedance formatching the acoustic impedance of free space to the acoustic impedanceof microphone 14 and a'coustic generator 16, respectively, for moreefficiently coupling acoustic signals therebetween. This is desirablesince the acoustic impedance of air is relatively low com pared to therespective acoustic impedances provided by microphone 14 and acousticgenerator 16 which ordinarily would provide a relatively ineflicientcoupling of signals therebetween.

More particularly, acoustic horn 15, responsive to an acoustic signalpropagating in free space, provides a path of increasing impedance forcoupling this acoustic signal to microphone 14 so that the impedancepath provided by ou ic. 1 011 1 .-c use t e a ous s a s coupled toappear amplified. Microphone 14 then converts the acoustic signalsuplied thereto by horn to a substantially nonacoustic or. electricalsignal for useby circuitry in fthe t'ran'sceiver. In the reversedirection, acoustic horn l5 also provides a' path of decreasingvimpedance for coupling the, second acoustic signal from acousticgenerator 16Ito free :space with increased audibility. It is, of courseassumed that both acoustic signals will not be coupled through acous tichorn 15 at the same time'if any adverse interaction may thereby occur.Moreover, more than one such acoustic born 15 may be included in anapparatus 10. where feasible.

. FIG..2 additionally, depicts tuning means, inductance 17,connectedbetween antenna plates 12 and 13 for tuning the antenna 11 tocompensate for the capacitive effects of dielectric between antennaplates 12 and 13; acoustic horn 15 together with air in the volume ofspace between I I 1nvention,'-another form of integral antenna andacoustic the plates comprisingat least a portion of this dielectric. Themagnitude of inductance 17 is usually selected as is known to thoseskilled in the art of antenna design, to provide together with thecapacitive effectof the antenna scribed with reference oac s ceenera ml-As usti dielectric, a resonant circuit at the frequency at whichantenna. 11 is who utilized, thereby substantially cancelling thecapacitive eifect of the dielectric between plates 12 and 13.

For convenience, apparatus 10 in this embodiment has been shown toinclude two types of transducer means,

units 14 and 16, and acoustic horn 15 has been described as having twomodes of operation. In one mode, as previously noted, acoustic horn -15provides a path of increasing impedance and, in the other, a path ofdecreasing impedance. However, it should be realized and as will beshown by way of example in later described embodiments also inaccordance with the invention, acoustic horn 15 may in some instancesprovide only one mode of operation and, likewise, apparatus 10 mayinclude only one transducer means. Also, where appropriate, a singletransducer may be utilized to perform both microphone 14 and acousticgenerator 16 functions. It should be further noted that, if desired, theacoustic path for microphone 14 need not ne'cessarily include the lengthof acoustic horn 15, but could be ported or coupled from microphone 14directly into or near the horn 15 opening, thereby essentially providinga more direct path from microphone '14 to free space.

OPERATION OF THE APPARATUS 0 F FIG. 2

In order to facilitate describing the operation and since only one modeof operation is provided in some embodiments, each of the two modes ofoperation previously referred to will be described separately.

In what may conveniently be referred to as a first mode of operation,a'coustic generator 16, responsive to a supplied electrical signal,converts the electrical signal to an acoustic signal. This acousticsignal is then supplied to the narrower end of acoustic horn 15 in anyconvenient manner such as via a short tube or like connecting device.The particular sizeand material of the connecting device being ofcourse, dependant upon the precise location of acoustic generator 16relative to the location of acoustic horn 15. The acoustic signalpropagates through acoustic born 15 and out the wider end of horn 15 tofree space. Acoustic horn 15 thereby provides a path of decreasingimpedance for more efiiciently coupling this acoustic signal fromacoustic generator v16, which has a relatively high acoustic impedance,to free space or air, which has a relatively low a'coustic impedance.Thus, the acoustic signal is coupled to free space with increasedaudibility.

In the second mode of operation, the. wider open end of acoustic horn-15is responsive to an acoustic signal locations; i t

horn 15 in this instance provides a path of increasing impedance for theacoustic signal so that the signal appears amplified upon reception atmicrophone 14. This latter mode of operation maybe jofparticular value,for example, where the" transceiver. containing acoil'sticflforn fi isphysically positionedat a location somwhafidistant from where variousconversations are likely 1 t o occuror when a person wishes totransmitvia the transceiver'but is required to whisper. The acousticsignal is converted to anelectrical signal which may subsequently hecoupled to appropriate transceiver circuitry (not shown) fortransmission via aritennadl to receiving units at other DESCRIPTION ANDOPERATION OF THE:';

EMBODIMENTS OEEIGS. 3, 4 and 5 FIGS. 3, '4 and 5 each depict,in-accordance with the horn'app'aratus 10. 'These'are shown,respectively, as apparatus 10a, apparatusltlb and apparatus 10c.Apparatus 10a, 10b and 10c'are constructed and: operate 'in amenneranalogous 'to that described with reference to ap? paratus 10 of FIG. 2.Apparatus 10aincludes 'elements Ila-14a, 16a and 17a' which correspondto like'elements 11-14, 1'6 and 17 of apparatus 1 0. -H0wever' by way'of example of some of the possible variations" of apparatus 10, onetransducer means, which would c'o'rresptindito microphone 14 in FIGLZ,isnot'included-in apparatus 10a. Thus, acoustic-horn 15a is utilized inone operating mode for more efficiently coupling theacoustic signal fromacoustic generator '16a'to free space. Elements which correspond-tomicrophone 14 are likewise not included in apparatus 10b and10cso thatacoustic horns 15b and 150 in these embodiments are likewise utilized inone operating mode, for more efficiently coupling; respective acousticsignals from acoustic generators- 16b and 160 tofreegspace. r

The embodiments of FIGS. 3, 4 and 5 ;eachi'di=;pi'ct in accordance withthe invention,ditferent physical arrange ments for acoustic "horns 15a,15b and 15p, respectively. These embodiments are constructed andwilljbe' described 7 with regard to the aforementioned first mode-erOperapropagating in'free space. This'a'coustic signal propagates tion.However, this is for convenience 'only," an'd"other modes such as theaforementioned second mode of operation or a combination thereof, areequally permissible with appropriate modification of the-transducermeans if necessary. v I

FIG. 3, for example, depicts acoustic horn-15a constructed of plastic orother dielectricmaterial and-inwhat may be referred to as a hollowconical shape, therebyapproximating' an exponential horn so that th'e'signal'co j. pled therefrom to free space appears amplified. I

Embodied in apparatus 10b of FIG.-4 is' a t'echniqu'e for increasing theapparent length of acoustic horn 15b while nevertheless having acoustichorn'f' 15b positioned within a fixed volume of space between antennaplates 12b and 13b. Various Otherdesired techniques for achiev ing thesame result may beemploy'ed, as appropriate. In the illustration ofFIG.4, the acoustic signalsiipplie'dby a'coustic'generator 16b iscoupled fromacoustic generator 16b to free space by being hanneledbetweensheets of dielectric material such as plastic, these sheetscomprising the acoustic horn15b; -Theacoustic "s i'gnal is' eliarineledinto successive corridors or paths bordered bya'p airof employs adifferent technique for increasing the apparent length of horn 15c.Pairs of solid plastic blocks, each pair being of the same or differentlength, but of successively decreasing volume, are mountedto the insidesurfaces of antenna plates 12c and 130 so as to comprise a channeltherebetween whichprovides successively increasing incremental volumesof space through which the acoustic signal is coupled to free space.Initially, the acoustic signal is coupled fromacoustic generator 16c tothe open end of the channel having the smallest volume of space. Thesignal then progresses or is coupled through the successively increasingincremental volumes until it reaches free space.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention and it is,-therefore, aimedto cover all such changes and modifications as fall within thetruespirit and scope of the invention.

What is claimed, is:

1. An integral antenna and acoustic horn apparatus usable in a portablecommunications unit, said apparatus comprising:

an antenna including two plates having a prescribed separationtherebetween, the separation between said plates defining a volume ofspace; I transducer means responsive to a supplied signal for convertingsaid supplied signal into another predetermined type of signal; anddielectric acoustic horn means positioned within the volume between saidantenna plates and coupled to said transducer means for matching theacoustic impedance of free space to the acoustic impedance of saidtransducer means for more efiicientlycoupling an. acoustic signaltherebetween, said acoustic horn togetherwith air in said volumecomprising dielectric between said antenna plates so that said impedancematching is provided withoutany appreciable degradation ofv the antennaperformance.

2. An antenna and-acoustic horn apparatus as described in claim 1,which, further includes tuning means coupled between said antenna platesfor use in tuning said antenna to compensate for the effects ofdielectric between said plates. i v i v 3. An antenna and acoustic hornapparatus as described in claim .1, wherein the two antenna plates aresubstantially parallel to each other.

4. An antenna and acoustic horn apparatus as described in claim 1,wherein said transducer means converts a supplied substantiallynonacoustic signal to a subsubstantially acoustic signal to be suppliedto said acoustic horn means. and wherein said acoustic horn meansprovides a path of decreasing impedance for coupling said acousticsignal fromsaid transducer means to free space with increasedaudibility. k

.5. An antenna and acoustic horn apparatus as described in. claim 1,wherein said two antenna plates are substantially parallel to eachother, said transducer means converts a supplied substantiallynonacoustic signal to a substantially acoustic signal to be supplied tosaid acoustic horn means, said acoustic horn means provides a path ofdecreasing impedance for coupling said acoustic signal from saidtransducer means to free space with increased audibility, and whereinsaid apparatus further} includes tuning means coupled between saidantenna plates for use in tuning said antenna to compensate for theeffect of dielectric between said plates.

6. An antenna and acoustic horn apparatus as described in claim 1,wherein said acoustic horn means, responsive to a substantially acousticsignal propagating in free space, provides a path of, increasingimpedance for coupling said acoustic signal to the transducer means sothat the impedance path provided by said acoustic horn means causes theacoustic signal so coupled to appear amplified, and

wherein said transducer means converts said acoustic signal suppliedfrom said horn means to a substantially non acoustic signal.

7. An antenna and acoustic horn apparatus as described in claim 1,wherein said two antenna plates are substantially parallel to eachother, said acoustic horn means, responsive to a substantially acousticsignal propagating in free space, provides a path of increasingimpedance for coupling said acoustic signal to the transducer means sothat the impedance path provided by said acoustic horn means causes theacoustic signal so coupled to appear amplified, said transducer meansconverts the acoustic signal supplied from said horn means to asubstantially nonacoustic signal, and wherein said apparatus furtherincludes tuning means coupled between said antenna plates for use intuning said antenna to compensate for the effect of dielectric betweensaid plates.

8. An antenna and acoustic horn apparatus as described in claim 7,wherein said apparatus further includes second transducer meansresponsive to a second supplied signal for converting said secondsupplied signal into a second acoustic signal which is supplied to saidacoustic horn means, and wherein said acoustic horn means additionallyprovides a path of decreasing impedance for coupling said secondacoustic signal from said second transducer means to free space withincreased audibility. y

9. An integral antenna and acoustic horn apparatus usable in a portablecommunications unit, said apparatus comprising:

an antenna including two substantially parallel plates having aprescribed separation therebetween, the separation between said platesdefining a volume of space;

transducer means responsive to a supplied substantially nonacousticsignal for converting said nonacoustic signal into a substantiallyacoustic signal to be supplied to an acoustic horn; dielectric acoustichorn means positioned within the volume between said antenna plates, forproviding a path of decreasing impedance to match the acoustic impedanceof free space to the impedance of said transducer means for moreefliciently coupling the acoustic signal supplied from the transducermeans to free space with increased audibility, said acoustic horntogether with air in said volume comprising dielectric between saidantenna plates so that said impedance matching is provided without anyappreciable degradation of the antenna performance;

and tuning means coupled between said antenna plates for use in tuningsaid antenna to compensate for the effect of dielectric between saidplates. 10. An antenna and acoustic horn apparatus as described in claim9, wherein said tuning means provides inductance for compensating forthe capacitive effect of dielectric between said plates.

11. An integral antenna and acoustic horn apparatus usable in a portablecommunications unit, said apparatus comprising:

an antenna including two substantially parallel plates having aprescribed separation therebetween, the separation between said platesdefining a volume of space;

transducer means rssponsive to a substantially acoustic signal from anacoustic horn for converting said acoustic signal into a substantiallynonacoustic signal;

dielectric acoustic horn means positioned within the volume between saidantenna plates and coupled to said transducer means, for providing apath of increasing impedance to match the acoustic impedance of freespace to the acoustic impedance of said transducer means for moreefficiently coupling the acoustic signal from free space to thetransducer means so that the acoustic signal thereby coupled appearsamplified, said acoustic horn together with air in said V a volumecomprising dielectric between said antenna References Cited,

plates so that said impedance matching is provided N T STATES PATENTSWithout any apprec1able degradation of the antenna 53 1/1951 Rims 32516and tuning means coupled between said antenna plates for use in tuningsaid antenna to compensate for the y effect of dielectric between saidplates. ROBERT GRIFFIN Primary Exammer 12. An antenna and acoustic hornapparatus as de- JAMESA. BRODSKY, Assistant Examiner scribed in claim11, wherein said tuning means provides 10 V inductance for compensatingfor the capacitive effect of dielectric between said plates. I e 325 24,130, 372; 343-720 Perfmmance; 5 2,749,435. 6/1956 Rinesetall 32578(UX

